What does it mean to be homozygous?

Being homozygous means that an individual has two identical alleles for a specific trait. This can occur in either a dominant or recessive form. For example, if an organism has two alleles for a trait related to flower color, and both alleles code for red flowers (RR), the organism is considered homozygous for that trait.

Understanding the concept of homozygosity is crucial in genetics because it can affect how traits are expressed in offspring. When an organism is homozygous, it can produce gametes that all carry the same genetic information for that trait, which often leads to a predictable phenotypic expression in the next generation. In contrast, being heterozygous, which involves having different alleles for a trait, can result in a blending of characteristics, making trait prediction more complex.

Trait variations within a single species and traits associated with crossbred organisms do not pertain to the definition of homozygosity directly, and having two different alleles for a trait clearly defines heterozygosity rather than homozygosity.